A sample implementaion of replacing a CT findOne controller to work with a slug instead of an id for Strapi v4

findOne-by-slug-strapi-v4.md

Implementing findOne by slug

Create the content type

For this example we will be using the article collection content type defined below for the implementation

path: /strapi-project/src/api/article/content-types/article/schema.json

{
  "kind": "collectionType",
  "collectionName": "articles",
  "info": {
    "singularName": "article",
    "pluralName": "articles",
    "displayName": "Article"
  },
  "options": {
    "draftAndPublish": true
  },
  "pluginOptions": {},
  "attributes": {
    "title": {
      "type": "string"
    },
    "slug": {
      "type": "uid",
      "targetField": "title"
    }
  }
}

Override the Content Type Controller

We can then customize the findOne controller to accept a slug over id

path: /strapi-project/src/api/article/controllers/article.js

"use strict";

/**
 *  article controller
 */

const _ = require("lodash");
const {
  transformParamsToQuery,
  pickSelectionParams,
} = require("@strapi/strapi/lib/services/entity-service/params");
const { createCoreController } = require("@strapi/strapi").factories;

const ENTITY_UID = "api::article.article";

module.exports = createCoreController(ENTITY_UID, ({ strapi }) => ({
  async findOne(ctx) {
    const { id } = ctx.params;
    const queryParams = ctx.query || {};

    // build default query structure
    const query = transformParamsToQuery(
      ENTITY_UID,
      pickSelectionParams(queryParams)
    );

    // add slug constraint to all requests
    _.set(query, ["where", "slug", "$eq"], id);

    const entity = await strapi.db.query(ENTITY_UID).findOne(query);

    // sanitize response to ensure permissions are respected
    const sanitizedEntity = await this.sanitizeOutput(entity, ctx);

    // transform response to uniform API response format
    return this.transformResponse(sanitizedEntity);
  },
}));

Note: The where parameter here is of the WhereParameter type

Query the endpoint by slug

The endpoint can then be queried by slug instead of id

http://localhost:1337/api/articles/lorem-ipsum

which will return the following response

{
  "data": {
    "id": 1,
    "attributes": {
      "title": "lorem ipsum",
      "slug": "lorem-ipsum",
      "createdAt": "2022-04-06T03:53:11.345Z",
      "updatedAt": "2022-04-06T03:53:24.671Z",
      "publishedAt": null
    }
  },
  "meta": {}
}

A not found error will be returned if no entities for the content type match the provided slug.

strapi-plugin-slugify

If you want all of this handled for you with multiple content type support, additional control over the slugification process as well as other useful features I would recommend the strapi-plugin-slugify.

Hey @ComfortablyCoding Thank you so much, this worked!